Effective extraction of triazines from environmental water samples using magnetism-enhanced monolith-based in-tube solid phase microextraction

Portable stirring device for the on-site extraction of environmental waters using magnetic hydrophilic-lipophilic balance tape

The spatial heterogeneity of environmental systems makes sampling at multiple locations crucial to provide complete and representative information. The on-site application of an extraction technique simplifies the sampling logistics, increasing sample integrity during transportation and storage. This article presents a portable, simple, and low-cost device capable of performing the simultaneous on-site extraction of several environmental water samples. The device consists of a small electric motor integrated into the plastic cap of a conventional glass bottle and operated with a portable battery. The electric motor provides stirring to a novel magnetic sorptive phase based on the deposition of hydrophilic-lipophilic balance (HLB) particles over a magnetic tape. The use of open technology makes the device globally affordable. In this first approach, the isolation and preconcentration of atrazine and simazine have been selected as proof of concept. Using an internal standard made unnecessary the adjustment of the ionic strength before the extraction, thus simplifying the analytical procedure. Under the optimum conditions and using direct infusion mass spectrometry as the instrumental technique, detection limits as low as 15 ng/L were obtained. The precision calculated at three different levels was better than 8.3%. The accuracy, calculated with spiked samples, indicates the applicability of the approach for environmental water analysis.

Development of magnetism-assisted in-tube solid phase microextraction of phenolic acids in fruit juices prior to high-performance liquid chromatography quantification

Magnetism-assisted in-tube solid phase microextraction based on porous monolith mingled with Fe₃ O₄ nanoparticles was developed for capture of phenolic acids in fruit juices. First, poly (1-allyl-3-methylimidazolium bis [(trifluoro methyl) sulfonyl] imide-co-ethylene dimethacrylate) monolith embedded with Fe₃ O₄ nanoparticles was facile fabrication in a capillary and employed as microextraction column. Subsequently, a magnetic coil adopted to produce variable magnetic fields during extraction stage was twined on the microextraction column. The analytes contents in eluant were quantified by high performance liquid chromatogram with diode array detector. Various parameters affecting the extraction performance were inspected and optimized in detail. Results revealed that the exertion of magnetic fields in adsorption and desorption steps enhanced the extraction efficiencies of analytes from 44.9-64.0% to 78.6-87.1%. Under the optimal extraction factors, the limits of detection were between 0.012 and 0.061 μg/L, relative standard deviations for precision in terms of intra- and inter-day assay variability ranged from 1.9 to 9.8%. The introduced approach was successfully applied to simultaneously quantify the contents of five analytes in real fruit juices with satisfying fortified recoveries (80.1-116%). The obtained results well demonstrate the promising potential of the developed method in the highly sensitive quantification of trace phenolic acids in complex samples.

Recent advances in the extraction of triazine herbicides from water samples

Pesticides are excessively used in agriculture to improve the quality of crops by eliminating the negative effects of pests. Among the different groups of pesticides, triazine pesticides are a group of compounds that contain a substituted C₃ H₃ N₃ heterocyclic ring, and they are widely used. Triazine pesticides can be dangerous for humans as well as for the aquatic environment because of their high toxicity and endocrine disrupting effect. However, the concentration of these chemical compounds in water samples is low. Moreover, other compounds that may exist in the water samples can interfere with the determination of triazine pesticides. As a result, it is important to develop sample preparation methods that provide preconcentration of the target analyte and sufficient clean-up of the samples. Recently, a wide variety of novel microextraction and miniaturized extraction techniques (e.g., solid-phase microextraction and liquid-phase microextraction, stir bar sorptive extraction, fabric phase sorptive extraction, dispersive solid-phase extraction, and magnetic solid-phase extraction) have been developed. In this review, we aim to discuss the recent advances regarding the extraction of triazine pesticides from environmental water samples. Emphasis will be given to novel sample preparation methods and novel sorbents developed for sorbent-based extraction techniques.

Applications of porous frameworks in solid-phase microextraction

Porous frameworks are a term of attracting solid materials assembled by interconnection of molecules and ions. These trendy materials due to high chemical and thermal stability, well-defined pore size and structure, and high effective surface area gained attention to employ as extraction phase in sample pretreatment methods before analytical analysis. Solid-phase microextraction is an important subclass of sample preparation technique that up to now different configurations of this method have been introduced to get adaptable with different environments and analytical instruments. In this review, theoretical aspect and different modes of solid-phase microextraction method are investigated. Different classes of porous frameworks and their applications as extraction phase in the proposed microextraction method are evaluated. Types and features of supporting substrates and coating procedures of porous frameworks on them are reviewed. At the end, the prospective and the challenges ahead in this field are discussed.

Application of magnetic nanomaterials in magnetic in-tube solid-phase microextraction

Development of magnetic nanomaterials has greatly promoted the innovation of in-tube solid-phase microextraction. This review article gives an insight into recent advances in the modifications and applications of magnetic nanomaterials for in-tube solid-phase microextraction. Also, different magnetic nanomaterials which have recently been utilized as in-tube solid-phase microextraction sorbents are classified. This study shows that magnetic nanomaterials have gained significant attention owing to large specific surface area, selective absorption, and surface modification. Magnetic in-tube solid-phase microextraction has been applied for the analysis of food samples, biological, and environmental. However, for full development of magnetic in-tube SPME, effort is still needed to overcome limitations, such as mechanical stability, selectivity and low extraction efficiency. To achieve these objectives, research on magnetic in-tube SPME is mainly focused in the preparation of new extractive phases.

In-tube solid-phase microextraction: Current trends and future perspectives

In-tube solid-phase microextraction (IT-SPME) was developed about 24 years ago as an effective sample preparation technique using an open tubular capillary column as an extraction device. IT-SPME is useful for micro-concentration, automated sample cleanup, and rapid online analysis, and can be used to determine the analytes in complex matrices simple sample processing methods such as direct sample injection or filtration. IT-SPME is usually performed in combination with high-performance liquid chromatography using an online column switching technology, in which the entire process from sample preparation to separation to data analysis is automated using the autosampler. Furthermore, IT-SPME minimizes the use of harmful organic solvents and is simple and labor-saving, making it a sustainable and environmentally friendly green analytical technique. Various operating systems and new sorbent materials have been developed to improve its extraction efficiency by, for example, enhancing its sorption capacity and selectivity. In addition, IT-SPME methods have been widely applied in environmental analysis, food analysis and bioanalysis. This review describes the present state of IT-SPME technology and summarizes its current trends and future perspectives, including method development and strategies to improve extraction efficiency.

Magnetic fiber headspace solid-phase microextraction coupled to GC-MS for the extraction and quantitation of polycyclic aromatic hydrocarbons

A technique was developed for magnetic fiber headspace-solid phase microextraction (MF-HS-SPME) of polycyclic aromatic hydrocarbons (PAHs). The efficiency of the extraction of a steel SPME fiber coated with an aminoethyl-functionalized SBA-15 (Santa Barbara Amorphous 15; a nanoporous sorbent) is substantially improved after its magnetization during HS-SPME. The effects of magnetic field strength, extraction temperature, extraction time, moisture content of the sample, desorption time and desorption temperature were optimized using a simplex method. The application of a moderately strong magnetic field to the fiber results in up to 135% increase in the extraction efficiency and wider linear dynamic ranges. The PAHs (specifically naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene and pyrene) were then quantified by GC-MS analysis. Comparison of an electromagnet and a permanent magnet indicated the superior effect of the permanent magnet for the target analytes due to the Ohmic heating of the magnetic coil and its negative effect on the extraction of some of the PAHs. The limits of detections of the PAHs are between 0.17 to 0.57 ng g^-1 by using the electromagnet, and between 0.10 and 0.32 ng g^-1 for the permanent magnet. Relative standard deviations of 2.9 to 7.6% were obtained for six replicated analyses of the analytes. The method was applied to some polluted soil samples, and satisfactory results were obtained. Graphical abstract Schematic representation of the designed magnetic fiber headspace solid-phase microextraction (MF-HS-SPME) system using (a) an electromagnet, (b) a pair of permanent disc magnets.

Enhanced magnetic ionic liquid-based dispersive liquid-liquid microextraction of triazines and sulfonamides through a one-pot, pH-modulated approach

In this study, an enhanced variant of magnetic ionic liquid (MIL)-based dispersive liquid-liquid microextraction is put forward. The procedure combines a water insoluble solid support and the [P₆₆₆₁₄⁺][Dy(III)(hfacac)₄^-] MIL, in a one-pot, pH-modulated procedure for microextraction of triazines (TZs) and sulfonamides (SAs). The solid supporting material was mixed with the MIL to overcome difficulties concerning the weighing of MIL and to control the uniform dispersion of the MIL, rendering the whole extraction procedure more reproducible. The pH-modulation during extraction step makes possible the one-pot extraction of SAs and TZs, from a single sample, in 15 min. Overall, the new analytical method developed enjoys the benefits of sensitivity (limits of quantification: 0.034-0.091 μg L^-1) and precision (relative standard deviation: 5.2-8.1%), while good recoveries (i.e., 89-101%) were achieved from lake water and effluent from a municipal wastewater treatment plant. Owing to all of the above, the new procedure can be used to determine the concentrations of SAs and TZs at levels below the maximum residue limits.

Removal of triazine-based herbicides on specific polymeric sorbent: fixed bed column studies

The porous material containing carboxyl groups was investigated in fixed bed system for the triazine-based herbicides removal from aqueous solution. In order to obtain adsorbent capable of generating specific interactions with triazines, the poly(divinylbenzene) was synthesized in radical suspension polymerization and then was modified with maleic anhydride in Diels-Alder reaction with subsequent base hydrolysis. The introduction of carboxyl groups into polymer structure resulted in obtaining specific interactions, such as hydrogen bonds between modified poly(divinylbenzene) and triazines, therefore the selectivity and the high adsorption capacity towards terbuthylazine, propazine, atrazine and simazine was observed. The total and usable adsorptive capacities, the breakthrough and exhaustion times, the coefficients of sphericity of isoplanes, the heights of adsorption fronts and the mass exchange moving rates were calculated based on the analysis of the breakthrough curves. Results show that the best sorption parameters in dynamic conditions were achieved for terbuthylazine and propazine. For them the highest values of adsorptive capacities, the smallest heights of mass transfer fronts and their slow movement along the bed height were obtained. The use of ethanol for herbicides elution provided a high recovery degree of adsorbed substances. Reusability of investigated polymer bed was studied in three adsorption/desorption cycles.

Dispersive Liquid-Liquid Microextraction in the Analysis of Milk and Dairy Products: A Review

Dispersive liquid-liquid microextraction (DLLME) is an extraction technique developed within the last decade, which involves the dispersion of fine droplets of extraction solvent in an aqueous sample. Partitioning of analytes into the extraction phase is instantaneous due to the very high collective surface area of the droplets. This leads to very high enrichment factors and very low solvent consumption, relative to other liquid or solid phase extraction methods. A comprehensive review of the various modes of DLLME in the analysis of organic and inorganic analytes in dairy products (milk, cheese, infant formula, yogurt, and breast milk) is presented here. Dairy products present a complex sample matrix and the removal of interfering matrix components can prove troublesome. This review focuses on sample pretreatment prior to the appropriate DLLME procedure, the extraction and dispersive solvents chosen, derivatisation methods, and analytical figures of merit. Where possible, a critical comparison of DLLME methods has been undertaken. The overall suitability, and limitations, of DLLME as a sample preparation technique for dairy products has been assessed.